1. Field of the Invention
This invention relates to the field of power systems and more specifically to the field of extending the life of battery powered systems.
2. Background of the Invention
There has been an increasing need to extend the uptime for battery powered devices while also extending the life of the devices. Traditional battery powered devices are only operable for a finite time as traditional batteries have a limited useful life. In addition, the devices are typically inoperable or unusable when their batteries are being charged. When the batteries are sufficiently charged, the device again becomes available. Besides the device downtime involved, further drawbacks include battery memory and reduction in battery life.
For instance, in the field of sensor networks, access to a power grid is typically unavailable. Therefore, the devices are typically independent. A typical drawback is trading off device/network lifetime versus the ability for the devices to transfer data between nodes. Traditional charging schemes either allow the device to run and communicate or allow the device to charge the battery.
Battery powered devices recharged by alternate energy sources have been developed to extend battery life. However, such alternate energy sources typically do not provide enough energy to support full device operation while storing energy for later use. Additional drawbacks include the effects of battery memory because of prematurely discharging the battery before it finishes charging.
Because battery life and uptime can be quality measures of battery powered devices, there is a need for maximizing the lifetime and uptime of an individual independently powered device. Additional needs include increasing the lifetime and uptime of individual powered devices that consume large amounts of power. Further needs include operating an independently powered device while at the same time charging its batteries. In addition, needs include maximizing use of alternate energy sources.